Reductions in recurrence in women with early breast cancer entering clinical trials between 1990 and 2009: a pooled analysis of 155746 women in 151 trials

An EBCTCG pooled analysis from 151 trials in early breast cancer which enrolled between 1990 and 2009 demonstrated a fall in distant recurrence rates in more recent calendar periods of enrolment. Most of this improvement was related to an increasing proportion of patients with lower stages and other characteristics of lower risk disease, but after adjustment for this, and the effects of improved treatment, the rates  of recurrence were still lower by around 19% in ER negative and 25% in ER positive disease. The possible effects of unrecorded elements of stage migration not could not be eliminated.  These results are useful for the planning of future clinical trials.